Propeller hub



April 2'1, 1931. D. G. LILLEY PRPELLER HUB Filed May 24, 1929 2 Sheets-Sheet l Cuba/mut April 21, 1931.

D. G. LILLEY PROELLER HUB Filed May 24, 1929 c C E E 2 sheets-sh'eet 2 fff Swanton may Patented Apr. 2l', 1931 l l i i UNITED STATES PATENT-cruce Damm. c. LILLEY, or DENVER., cononano IPBOPELLCER HUB Application led Hay 24, 1929. Serial No. 365,703.

This invention relates to im rovements in Fig. 1 is an end view of the propeller hub the construction of propellers or aerqplanes' looking in the direction of arrow l in Fig. 2; and has reference more particularly to an m- Fig. 2 is a sectiontaken on line 2 2, proved hub construction which isv especially Fi l;

5 adapted for use with variable pitch propel- 'g. 3 is a section taken on line 3 3, 55

1ers of the type described and claimed in Fi 2; f I

\ U. S.- Letters Patent 1,7 12,708,1da'ted May 14, ig. 4 is a section taken on line 4 4,

' y It is well lmownamong those havin ex- Fig. 5 is a section showing `a slightly 1 perience with the operation of aeropanes modified form of construction; and j 0 and airships that much better operation F1g. 6 is a. section taken on line 6 6, would be obtained if it were possible to Flg. 5. change the pitch of the propellers while the A In the drawings numeral 1 represents one ship is in operation., The question of conof the main bearings of the engine and 2 the 1 5 structing a-practical variable pitch propeller propeller drive shaft which may be a pro.-

has been found to involve some very diiicult longation of the engine crankshaft. Secured mechanical problems and roblems of design to the outer end of bearing l is a bearing' which apparently has so ar not been solved sleeve 3, whose outer end is threaded lfor in a satisfactory manner. the reception of a nut 4.-. This sleeve is pro'-I 7 It is the-object of this invention to produce vided with one or more grooves 5 and carries o a hub'construction which shall be adapted to a friction gear 6 which has two friction sur` be employed in connection with the mechafaces 7. l This gear is provided with a spline 8 nism described and claimed inthe .patent that engages the. groove 5 and holds the gear above identified for rotating the blades and against rotation. Links 9 connect the hub -75 changing their pitch while in operation. 10 and gear 6 with cranks 11 which are se- It is evident that propellers of the type to vcured to the shaft 12. This shaft can be r0- A which this invention relates, are subjected tated by means of a link 13 that is connected to very severe strains, some of which are due with the control lever 14. This lever is held to centrifugal force and others of which are in adjusted position by means of a quadrant due tothe bending strains resulting from the 15. The mechanism which is employed for 80 resistance offered by the air to the rotation of varying the pitch of the propell'ers and which the propellers. AA propeller hub construchas partly been described forms the subject tion must, of courseQbe of a very strong conmatter of the patent above identified and will struction so as to enable it to successfully revtherefore not be describedV in this applicasist the severe strains and when, as in this tion with any greater detail than necessary 8 case', the. pitch of the blades are to be varied for the vpurpose ofv explaining the invention. while thel propeller is rotating suitable thrust The propeller drive shaft is provided with a r bearingsmust be provided which must beso taperedend portion 16, whose outer end is, `v designed that they will resist the powerful threaded for the reception-of a nut 17. Seforces due to centrifugal `action and which cured to the tapered end of the shaft is the will at the same time` permit the propeller hub of the propeller. This hub is formed blades to be rotated. from a single unitary steel casting having a The above and other objects which may central portion '18, which isprovided with a 45.become apparent as the description proceeds tapered opening for the reception of the are attained by means of a construction and shaft. Two or more radial Varms extend out- 5 `an arrangement of parts that will now be wardly fromthe'central portion. These arms described in/detail, reference for this purpose are integral with the central portion andare bein hadto the accompanying drawings in provided with radial openings through which whii the preferred embodiment of my inthe cylindrical root portions 19 ofthe propel- 100 50. vcntionv has been illustrated, and'in which: ler blades extend. These radial openings have their outer ends tapered as indicated by reference numeral 20 and located within the tapered portion of each radial opening is a split bearing ring 21, whose outer surface is tapered to conform with the taper of the openings in the arm. A ring 22 has a threaded engagement with the inner threaded surface 23 and serves to move the rings 20 inwardly and to hold them in adjusted position. Set screws 24 hold the rings 22 against rotation so that the parts will remain in adjusted position. Each arm has a rectangular recess or opening 25 extending inwardly from the following side of the hub and this opening communicates with the radial openings above referred to. At the innermost ends of the radial openings the recesses 25 terminate in planes 26 that coincide with the axes of these openings, all as shown in Fig. 4. A removable bearing cap 27 is held in place by means of bolts 28 and serves to enclose the inner end of each root portion. Split bushings 29 may be interposed between the inner ends of the root portions 19 and the adjacent surfaces of the hub and the bea ring caps. These bushings may be made of a suitable metallic alloy or may be of fiber or some nonmetallic composition whichever may be found to be most desirable. The cylindrical root portions 19 are provided with threaded sections 30 with which the worm gears 31 are threadedly connected. The worm gears have one side provided with conical surfaces 32 which co operate with the tapered rollers 33 and with the annular roller races 34 to form thrust bearings which resist the centrifugal force 'that is generated during the rotation of the propellers and which also serve as part of the means for rotating the propeller for the purpose of varying its pitch. The outer end of each recess 25 extends entirely through the arm and forms an opening in which the worm 35 is located. 'These worms rotate in bearings that are formed in part by the caps 3G and cooperate with the worm gears 31 for the purpose of controlling the rotation of the propeller blades. The worm gears 31 are eld against rotation by means of keys 37 that are of such length that they can be inserted after the root portions 19 have been put into place as shown in Fig. 3. For the purpose of inserting and removing these keys the bearing caps 27 must be removed. Referring now more particularly to Fig. 2, it will be seen that worms 35 are provided with longitudinal openings 38 whose sides are provided With diametrically located slots or grooves 39. Screws 40 extend into the openings 38 and are provided with outwardly extending fins 41 that engage the grooves 39. So that the screws may move longitudinally within the worms without having any relatively rotary movement therewith. The screws 40 extend through bearings whose inner surfaces are threaded'. These bearings are formed in part by caps 42, and the outer end of each screw'is provided with a friction gear 43 having a bevelled surface 44. One of these gears are located on each side of the gear 6 and the latter can therefore be moved into contact with either gear 43. In Fig. 1 I have shown how the two worms 35 are interconnected by means of a train of gearslcomprising a plurality of gear wheels 45.

Let us now assume that the hub shown in Fig. 3 is rotated in a connterclockwise direction. The resistance due to the movement of the fan blades through the air produces a force, one component of which has been designated by arrow 46. This force tends to move the inner ends of the root portions downwardly against the bottom of the opening which is formed in the integral portion of the hub. ,y means of the adjusting nut 22 the split ring 2O can be moved inwardly so as to produce the desired fit between it and the surface of the corresponding root portion. The centrifugal forces are resisted by the thrust bearing which has been described herein. The side walls 47 which extend from the central portion of the hub to the integral end portions 48 of thearms may have as great depth as may be necessary to resist the strains produced by the operation of the propeller and may have sufficient thickness to give them the desired strength to withstand' all the strains to which they will be subjected.

Attention is called to the fact that the bearing caps 27 are not called upon to resist any severe strains as the forces due to the air resistance are in the opposite direction, and thereforethe function of these caps consists in holding the inner ends of the root portions against movement away from the bottoms of the bearings.

T he openings 25 are provided for the purpose of inserting and removing the worm gear wheel 50 and the thrust bearing. In order to obtain the maximum strength and rigidity, the hb has been formed from a single piece of steel with a central opening for the reception of the end 16 of the drive shaft and with radial arms. 'Each arm comprises two walls 47 that are spaced the width of opening 25 and whose outer ends are joined by an integral transverse wall 48. The bottom of the opening 25 is on the leading side of the rotating arms and is therefore subjected to tension when the propeller operates. It is, of course, also subjected to flexure due to the tractive effort of the blades.

By making the hub from a single piece of metal, it will have the maximum strength and rigidity and therefore-it will notbe distorted to any appreciable extent during the operation. Since the end wall 48 is integral with the side walls land the bottom of the opening 25, it will withstand the centrifugal forces produced at hi h speed and therefore the bearings will not ind,v but will function are each provided with a struction brings the freely. If the hub were made of several pieces bolted or riveted together, it would be more liable to become distorted and its operation would be less satisfactory. The fact that the open side of opening 25 is on the following sideis of importance for by this means the maximum strength and rigidity is obtained and it is alsomossible to erted by the inner end of the blade roots on a bearing that is integral with the hub.

he construction above described gives to all intents and purposes a one-piece hub whose integral parts may be made of any suitable metal and so designed as to have sufficient strength to take care of the various forces` and strains to which it is operation.

Attention is called to the fact that the worms 35 are located substantially midway of the radial arms and that the forces which are necessary for rotating the propeller blade are resisted by the central portion of the propeller, thereby obviating the producsubjected during tion of -severe tortional strains which, if applied to the outer ends of the arms, might tend to distort them to a dangerous extent.

Figs. 5 and 6 I have shown a slightly modified form of construction in which the cylindrical root portions 19 are provided at their inner ends with threaded sections that have been designated by reference numeral 49. The worm wheels 50 are somewhat different in shape than the corresponding wheels 31 and long threaded hub ese worm wheels are held against rotatlon by means of keys 52. The outer surfacesv of the hubs 51 serve'as bearings and these extend into conical split rings 21a. hese rings are held in adjusted position by means of nuts 22a. The outer surfaces of the worm wheels have conical bearing surfaces 53 with which the rollers 33 cooperate. The annular raceway 34a rests against the inner side of the two spacing blocks 54 and 55. These blocks are made removable for the purpose of permitting the worm .wheels 50 to e inserted into the openings, and are held 1n place by means .of

rotating mechanism closer to the center and therefore diminishes to a still greater extent the torque which tends to distort the radial arms Whenthe propeller blades are adjusted. A

Attention is called to the fact that with the construction illustrated, it is possible to adjust the bearings so as to prevent any relative movement between the propeller blades and the hub except the rotary moveh ment necessary for adjustment. The conical split rings maintain theaxes of the propeller blades in exactly the same position after each wear. The removable bushand replaced if they should wear to any appreciable extent and it is therefore possible to nmaintain the enresist the force exbolts 56. This conb the root vradial arm having an opening tire assembly in proper adjustment ,at 'all times.

In the above description the hub construction has been explained in connection with the propeller blade rotating mechanism devscribed and claimed in the patent above identified, but I want it understood that this particular mechanism has been employed as an example of such meansonly and that the hub construction can be employed in connection with any other` means for rotating the blades.

Having described my invention what I claimy as new is:

1. A propeller hub having radial arms each formed from two parallel walls joined rigidly 'together by integral transverse walls. one

wall connecting the inner ends of the radial walls and a separate wall connecting the outer ends of each pair of arallel walls whereby a box-like opening is ormed in each parallel wall, the transverse end walls having openings through which the root portion of a propeller blade can extend and the wall connecting the inner ends of the radial walls having a bearing for the inner end of the root portion of the propeller blade.

2. A propeller hub formed from a single piece of metal, said hub having a plurality of radial arms,"each arm having a radial opening for the reception of the root portlon of a propeller blade, each of the radial arms having an opening extending into the same from the fol-lowing side, and a smaller opening extending into the radial o ning from the leading side, the inner end o the radial opening forming a bearing.

3. propeller hub for use with variable patch propellers, said hub comprising a single piece of steel having a central opening for the reception of a propeller shaft and a plurality of radial arms, each formed from two parallel, spaced walls lying in planes perpendicular to the axis of rotation, thel outer ends of the walls being integrally joined by a transverse ,wall which has an opening adapted to receive the root portion of a propeller blade, the leading edges of the spaced parallel walls eing connected by an integral wall member which forms the bottom of a recess whose other side is open, the end of the recess near est the center of the hub having a bearing for the reception propeller root portion.

4.. A propeller hub .formed from a slngle piece of steel, said hub having a solid central portion provided with an openingfor the reception of a propeller shaft, said hub aving a plurality of radial arms, each arm having a radial opening for the reception of portion of a propeller blade, each extending thereinto in the plane of rotation, and the inner end of the radial o ening of each arm having a bearing that is fldrmed in the central portion and which is adapted to, receive the of the inner portion of a,

inner end of the root portion of a propeller blade.

5. A propeller hub having radial arms each formed from two parallel walls lying in spaced planes and joined rigidly together by integral transverse walls, one Wall connecting the inner ends of the radial arms and a separate wall connecting the outer ends of each pair of parallel walls whereby a boxlike oponinplr is formed between each pair of parallel walls, the transverse end Wall having an opening through which the root portion of a propeller blade can extend and the wall connecting the inner ends of the radial arms havingr a bearing for the inner end of the root portion of the propeller blade.

In testimony whereof` l atiix my signature.

DANIEL G. LLLEY. 

